Automatic riveting machines generally include a drilling unit, a rivet supply unit, and a rivet setting unit also referred to as a rivet setter herein, These units are controllable by the central processing unit of the positioning robot.
The drilling unit and the rivet setter are mounted on a support console so that they are movable in a radial direction toward and away from a riveting location or position. Accordingly, respective guides for the drilling unit and the rivet setter extend radially toward the riveting position on the console. The operating cylinders, preferably pneumatic piston cylinder devices, move the respective unit into and out of the respective operating positions. The console carrying these units is docked to a robot which functions as a positioning device. The coupling between the positioning device and the console for the docking is accomplished by a multi-purpose coupling that permits mechanical, electrical, pneumatic and hydraulic connections.
German Patent DE-PS 3,232,093 correspond to U.S. Pat. No. 4,548,345 (Puritz etal.), issued on Nov. 22, 1981, discloses an automatic riveter as described above capable of automatically seeking out individual rivet locations for positioning the tools in such locations and this can be done even with regard to relatively complicated structural components. The Known riveter comprises essentially a drilling feed advance unit, a rivet supply unit, and a rivet setter, each of which is controllable, and all of which are mounted on a support console for a radial displacement toward and away from the riveting location. The known riveter is especially suitable for setting rivets in so called clip stringer connections in the aircraft construction, whereby an automatic feed advance toward and away from the rivet locations is performed. However, locations which are hard to access, e.g. overhead locations leave room for improvement. A rivet hole is drilled by the drilling unit which includes a drill feed advance device. The drill feed advance device includes a first guide body with a pneumatic or electric sensor and a second guide body carrying an angular drilling tool supported by a bore bushing guide system that can yield in a spring elastic manner. A sensor and the angular drilling tool are guided in parallel to each other from their resting position to the drilling position in alignment with a rivet location where the rivet hole is to be drilled. The conventional drill feed advance device has the disadvantage that the precision of the bore hole required for a precise rivet fit, e.g. a press-fit, and the countersinking required for a flush rivet or a flathead rivet, are not assured. Hence, there is more room for improvement.
The rivet supply unit in the conventional apparatus is brought into its working position after the drilling unit has been moved out of its working position back into its rest position. The feed advance of the rivet supply unit is performed so that the central axis of the previously drilled rivet hole coincides with the central axis of the end of the rivet supply tube, When this coincidence is established, a rive% is shot into the predrilled hole by compressed air. Since the rivet is positioned in the rivet hole with a play fit, the rivet is easily movable in the predrilled hole. As a result, the conventional riveter can work only when the deviation of the longitudinal rivet axis from the vertical position is smaller than 90.degree.. In other words, the supplied rivet prior to setting must be retained in the rivet hole by gravity. As a result, overhead working positions rotated by 180.degree. relative to the normal working position or any desired inbetween working position is not possible, except when the deviation from the vertical is smaller than 90.degree..
The rivet setter in the conventional rivet machine is brought into its working position after the rivet supply unit has been moved back into its rest position. The rivet setter is constructed as a so-called alligator rivet setter which comprises a fixed arm and a tiltable movable arm. The fixed arm carries at its forward end an inserted rivet setter. The tiltable arm carries at its forward end a flat anvil and a work piece holding pressure bushing for clamping the work pieces. The known alligator rivet setter operates in accordance with a scissors stroke setter, which means that a linear rivet setting motion does not exist. Even if the radius between the setting tool and the journal axis of the scissors is very long, which is not practical, the setting motion is still an angular motion, even in a very narrow angular range. This is so, because the components that perform the setting motion rotate about the journal axis of the scissors. As a result, the known rivet setter does not satisfy the high precision requirements and parallel, or rather linear motions for the setting of precision rivets. The known setter is also limited in its range for setting rivets having different rivet lengths.
Thus, the conventional riveter has the disadvantage that it cannot produce precision rivet connections set by squeezing. Such precision rivet connections require a rivet bore hole quality which is the same as that for press fits. Such connections require the pressing of the rivets into the rivet holes and a linear rivet setting squeezing motion. Another disadvantage is seen in the fact that overhead rivet connections cannot be made, nor rivet connections in which the rivet axis deviates by more than 90.degree. from the vertical so that the rivets can no longer be held by gravity in the rivet hole prior to the squeeze setting operation.